Recently, extinguishing oil well fires has become a matter of urgency, as exemplified in Kuwait following the Gulf war. Several methods already in use in Kuwait have proved very slow; as a result, many oil well fires are burning several months after the process of extinguishing began.
One of these methods is to approach the oil well fire with a massive charge of explosives mounted on the end of a protruding arm; when ignited (by remote control) near the burning oil wellhead, the exploding charge is intended to blow the fire out. The principle used here is the same as that used when blowing a candle out, except that it is done on a massive scale. The problem with this method is that although the exploding charge may effectively blow the fire out, it carries the risk of unintentionally reigniting the explosive gasses which are present, and so keeping the fire going. Since it is a "hit and miss" idea, it is not reliable. Sometimes this method is tried several times before success is obtained. Sometimes the well is abandoned and left burning.
Another method is to tunnel underground until the supply pipe is reached, then drill into the pipe and inject fire retardant chemicals or low viscosity mud into the well pipe to reduce the oil flow and, consequently, the fire's magnitude. Subsequently, the explosive charge method can be reapplied. The problem with this method is the time required to do the tunneling, subsequent drilling, and mud injection.
B. H. Cunningham, in U.S. Pat. No. 4,433,733, dated Feb. 28, 1984, shows a framework of tubular material which is covered with flexible material such as asbestos on its sides and top. The tubular framework has inwardly facing holes which can be supplied with a fire retardant fluid, such as water.
The problem with this method is that the use of asbestos is no longer considered environmentally acceptable, and no other lightweight fire resistant material exists to replace it. Another problem is that the pressure of escaping oil from an oil wellhead is so intense that lightweight materials would be destroyed before the fire could be extinguished. Also, because of its light weight, it would be buoyed up by the escaping oil column and the ascending heat, making it difficult or impossible to maneuver the device into place over the fire.
D. G. Thaxton, in U.S. Pat. No. 4,337,831, dated Jul. 6, 1982 shows a fire extinguishing apparatus for oil wells in which a bell nipple is constructed in position around an oil well pipe as a preventive measure. The apparatus has a plurality of containers which house fire extinguishing material, and is connected by conduit means, so that if a fire ever occurs, it can be quickly extinguished by metering the material through valves into the bell nipple.
The problem with this type of fire extinguisher is that it must be built before any fire occurs in the oil wellhead. It is not practical to bring the apparatus to where a fire already exists, due to the extreme heat and engineering needed to put the mechanism together to make it work.
U. Hefetz, in U.S. Pat. No. 3,973,631, dated Aug. 10, 1976, shows a method and apparatus for extinguishing oil well fires in wells having an inner pipe and an outer pipe separated by an annular space. The method involves drilling into both inner and outer pipes and inserting spikes radially to close off the pipes. In addition, any protective piping used around the oil and gas supply pipes must be first removed before work can be started in closing off the supply pipes. The problem with this method is that it is not possible for workers to get within 50 yards of the burning oil well fire due to the high temperature of the burning oil, let alone work on the oil well pipes above ground level.